1. Field of the Invention
The present invention relates to a two-layer imageable element including a substrate, a top layer including a first thermally imageable composition including a first thermally sensitive supramolecular polymer; and disposed between the substrate and the top layer, a bottom layer including a second thermally imageable composition including a second thermally sensitive supramolecular polymer. The thermally sensitive supramolecular polymer, which includes at least one covalently bonded unit and at least one thermally reversible non-covalently bonded unit that includes a two or more centered H-bond within each non-covalently bonded unit. More particularly, the present invention relates to a method of producing a two-layer imaged element.
2. Description of the Prior Art
WO 98/14504 discloses a supramolecular polymer containing monomeric units, which in pairs, form at least 4 H-bridges with one another. The article in J. Org. Chem., 53, 5787-9 (1988) discloses bifunctional compounds that can associate into polymers or oligomers by 2-center H-bond units. Supramolecular polymers based on 3-center H-bond units are disclosed in Macromolecules, 28, 782-83 (1995). None of the above references discloses the use of these polymers in thermal imaging.
EP 969 966 discloses phenolic polymers together with a non-photosensitive solubility inhibitor which provides acceptor sites for H-bonding and EP 985 166 discloses the corresponding methods. The present invention is directed to a supramolecular polymer having non-covalent interactions, such as H-bonding, as an integral part of the polymer structure. The H-bonding in the present invention is not between a H-donor polymer and a solubility inhibitor having H-acceptor sites, but is an integral part of the polymer structure.
WO 99101795 discloses phenolic polymers, which are modified with groups that provide acceptor sites for H-bonding with other phenolic polymers. The present invention is directed to a supramolecular polymer having non-covalent interactions as an integral part of the polymer structure.
An article by B. J. B. Folmer et al., Advanced Materials, Vol. 12 (No. 12), pages 874-878 (2000), discloses supramolecular polymer materials. The article does not disclose polymers derived from polyfunctional materials, such as, polyfunctional phenolic resin, acrylic resin, polyester resin or polyurethane resin, nor does it disclose the use thereof in thermal imaging.
U.S. Pat. No. 6,143,464 describes a thermal positive image forming material in a single layer system. The photosensitive layer has sea/island structure. Photosensitive composition includes a co-polymer including 10 mol % or more of at least one of: (a) a monomer having in the molecule a sulfonamide NH group, (b) a monomer having in the molecule an active imino group and (c) acrylamide, methacrylamide, acrylate, methacrylate or hydroxy styrene, each having a phenolic hydoxyl group.
JP 2000-330265-A describes a thermal positive image forming composition in a ingle layer system. The photosensitive composition includes a resin, which has a urea bond on a side chain. The resin is dissolved into alkaline aqueous solution.
EP 908305 describes a thermal positive photosensitive composition in a double layer system. The top layer is sensitive to IR-radiation. Bottom layer includes a resin, which is soluble in an alkaline aqueous solution.
EP 909657 describes a thermal positive image forming material in a double layer system. Top layer includes a resin having phenolic hydroxyl groups and an IR-dye. The bottom layer includes co-polymer having sulfonyl amide group.
The present invention describes a 2 layer system, wherein both top and bottom layers have a thermally sensitive supramolecular polymer containing a non-covalently bonded unit, such as, a quadruple hydrogen bonding (QHB) unit.